In light of energy prices and environmental concerns, processes for the production of fuels from renewable feedstocks are needed. The most common process involves producing ethanol from corn. Unfortunately, using corn and the like as precursors competes with food and feed supplies.
Some processes employ lignocellulosic biomass as a feedstock because it is readily available and competitively priced. Lignocellulosic biomass often comprises polymeric carbohydrates (cellulose and hemicelluose), complex poly-aromatics (lignin), extractives and ashes and thereby does not compete with food and feed supplies. For example, WO 2007/103858 describes using biomass-derived carbohydrates to form alkanes. An aldol condensation of acetone with furfural or 5-hydroxymethyl furfural (HMF) followed by reduction of the coupled product in hydrogen gives alkanes having from approximately 8 to 18 carbon atoms. Unfortunately, the described process has numerous disadvantages. For example, the reactions often require a high strength base. Moreover, the low degree of branching of the derived alkanes also results in low octane numbers which limit their use in gasoline.
Other processes of converting lignocellulosic biomass to useful forms of energy include gasification with subsequent conversion of the carbon monoxide/hydrogen syngas to liquid hydrocarbons via a Fischer-Tropsch reaction. Unfortunately, such processes typically require natural gas or petroleum products to produce the hydrogen. In sum, the production of practical fuels from biomass using prior art methods is inefficient and often cost prohibitive.
Accordingly, new processes are needed for use in making biofuels which are more efficient and more cost effective. Advantageously, new processes have been discovered that meets the aforementioned needs and more.
In one embodiment, a process for producing an energy source comprises step a) of first hydrolyzing a lignocellulosic feedstock in the presence of a hydrolyzing catalyst to form a first mixture comprising lignocellulosic hydrolyzate and a hydrolyzate residue. The lignocellulosic hydrolyzate is treated to produce a second mixture comprising hydrogen in step b). In step c) at least a portion of the hydrolyzate residue of the first mixture may then be reacted with hydrogen in the presence of a catalyst to yield an energy source.
In another embodiment, a process for producing an energy source comprises first hydrolyzing a lignocellulosic feedstock in the presence of water, alcohol, and carbon dioxide at a temperature of from about 220° C. to about 290° C. to form a first mixture comprising lignocellulosic hydrolyzate and a hydrolyzate residue. The lignocellulosic hydrolyzate may be reformed to produce a second mixture comprising hydrogen. At least a portion of the hydrolyzate residue of the first mixture may be reacted with at least a portion of the hydrogen produced in step b) in the presence of a catalyst to yield an energy source.
In another embodiment a liquid energy source is produced. The liquid energy source is derived from lignin and comprises from about 18 to about 28 percent by weight oxygen, from about 65 to about 84 percent by weight carbon, and hydrogen.